Cyclodisilazanes

ABSTRACT

Novel organosilicon compositions are prepared which contain silicon to nitrogen bonds which are attached to functional atoms and radicals. The novel compounds are used to prepare conventional siloxanes.

United States Patent [191 [111 3, Bush at a]. 1 June 26, 1973 CYCLODISILAZANES [56] References Cited [75] Inventors: Richard Paul Bush, Penarth; UNITED STATES PATENTS Norman Lloyd, Cardiff; 3 40 2 7 9 4 Christopher Arthur Pearce, 3,414,584 2 3 Cowbridge, all of Wales 3,532,728 10/1970 [73] Assignee: Dow Corning Limited, London, England v Filed; fl 3, 1971 Primary Examiner-Daniel E. Wyman Assistant Examiner-J. F. Shaver [21] Appl' 21l777 Att0rney-Roben F. Fleming, Jr., Laurence R.

Related US. Application Data Hobey et al. v [60] Continuation-impart of Ser. No. 68,786, Sept.. 1,

1970, abandoned, which is a division of Ser. No. 734,243, June 4, 1968, Pat No. 3,607,895. [57] ABSTRACT 7 Novel organosilicon compositions are prepared which [52] US. Cl 260/448.2 N contain silicon to nitrogen bonds which are attached to [51]. Int. Cl. C07f 7/10, C07d 109/04 functional atoms and radicals. The novel compounds [58] Field of Search 260/448.2 N

are used to prepare conventional siloxanes.

3 Claims, No Drawings 1 CYCLODISILAZANES This application is a continuation-in-part of application Ser. No. 68,786, filed Sept. 1, 1970 now abandoned, said application being a Divisional .of application Ser. No. 734,243, filed June 4, 1968, now granted as US. Pat. No. 3,607,895 and claiming priority under Title 35, US. Code, Section 1 19, from British Application No, 27067/67, filed June 12, 1967.

This invention relates to novel organosilicon compounds and to processes for their preparation.

Certain compounds which are characterized by the presence therein of three silicon atoms attached to a nitrogen atom are known. This invention is concerned in particular with the provision of novel compositions of this type which contain silicon-bonded functional atoms and radicals and which are, therefore, useful as intermediates in the preparation of other classes of silazane or siloxazane compounds. The invention is also concerned with novel compositions derivable from the compounds containing functional atoms or radicals attached to silicon.

According to this invention, there are provided novel organosilicon compositions of the general formula (XR Si) NSiR wherein X represents H, Cl, Br, I or a hydrocarbonoxy radical and each R and each R represent an alkyl radical containing less than six carbon atoms, an alkenyl radical or a monocyclic aryl radical.

The compounds of this invention in which X represents a hydrogen atom can be prepared by the reaction of an alkali metal derivative of a disilyl amino compound, the derivative having the formula (HR Si) NZ, wherein Z is an alkali metal atom, with a monochlorotriorganosilane of the general formula R' SiCl, R and R being as hereinbefore defined. Preferably, the alkali metal 2 is lithium but other alkali metals, for example, sodium and potassium, can be used provided they do not react preferentially with the silicon-bonded hydrogen atoms under the conditions of the reaction.

The reaction can be carried out in the presence of a solvent, for example, a hydrocarbon such as toluene or xylene or, more preferably, diethyl ether or tetrahydrofuran. Although some reaction occurs at lower temperatures, the preparation is best performed at temperatures above C. and most conveniently at the reflux temperature of the reaction mixture.

The alkali metal derivative reactants can be prepared by any known technique such as by the reaction of an organo lithium compound, e.g. n-butyl lithium, with the corresponding amino compound, for example, (HR Si) NH, in a hydrocarbon solvent such as pentane.

Compounds of this invention in which X represents a chlorine, bromine or iodine atom can be prepared directly from the analogous silicon-hydrogen containing compounds by halogenation of the silicon-bonded hydrogen atoms. The halogenation step can be performed A by any suitable technique, for example, in the case of the chlorination reaction by passing chlorine through a solution of the amino compound in an organic solvent, for example, carbon tetrachloride or benzene. When the halogen is bromine or iodine, it can be added to the organosilicon compound as a solution in an organic solvent. A'hydrogen halide acceptor, for example, pyridine or isoquinoline, should be present during halogenation in order to minimize the effect of the byproduced hydrogen halide on the amino-silicon compounds. The temperature at which the halogenation is carried out is not critical and temperatures from about 20C. to about 50C. have been found convenient.

The halogenated compounds can be converted to the hydrocarbonoxy derivatives, that is, where X is an alkoxy or aryloxy radical by reaction of the halogen atoms with the appropriate alcohol or phenol in the presence of a suitable hydrogen halide acceptor. Methods by which silicon-bonded halogen atoms can be converted to silicon-bonded alkoxy or aryloxy radicals will be well known to those skilled in the art. The hydrocarbonoxy derivatives can also be obtained as hereinafter described by reaction of a cyclodisilazane with an alcohol or a phenol.

The novel compounds of this invention represented by the general formula (XR Si) NSiR,-, wherein X is chlorine, bromine or iodine can be converted to reactive cyclodisilazanes by reaction with ammonia or an organic amine R"NH methylamine, ethylamine or aniline. The cyclodisilazanes are novel compounds having the structure wherein R" is derived from the ammonia or amine reactant and is hydrogen, an alkyl radical, for example, the methyl, ethyl, propyl or octadecyl radicals, an alkenyl radical such as the allyl radical or the phenyl radical, and R and R are as hereinbefore defined. Such cyclodisilazanes and the process for their preparation are also included within the scope of this invention.

Conveniently, the preparation of these cyclodisilazanes is carried out by passing NH or methylamine into a solution in an inert solvent of the compound of the general formula (XR Si) NSiR X being Cl, Br or I, at or about room temperature. The cyclodisilazanes are useful as crosslinking agents for organic or organosilicon compounds containing hydroxyl groups. They may also be reacted with such compounds to provide liquid or resinous polymers which are useful as lubricants, water repellents and coating materials.

When hydrolyzed, the novel cyclodisilazanes of this invention are converted to novel cyclic siloxazane compounds having the structure Such hydrolysis is best performed by mixing a solution of the cyclodisilazane in a water-immiscible solvent with approximately the theoretical quantity of water.

The cyclodisilazanes can also be converted to compounds of the formula (XR Si) NSiR' wherein X is an alkoxy radical or an aryloxy radical by reaction with an alcohol or a phenol.

In the general formula given herein, each R and each R can represent the same or different radicals and can be alkyl radicals containing less than six carbon atoms, for example, methyl, ethyl, propyl or butyl radicals, a1- kenyl radicals such as vinyl, allyl and cyclohexenyl radicals or monocyclic aryl radicals, for example, phenyl, p-tolyl or nitrophenyl radicals. The preferred compounds are those in which R and R are both methyl radicals. When the X substituents in the general formuiae are hydrocarbonoxy radicals, they are preferably selected from lower alkoxy and phenoxy radicals.

The following examples are illustrative of the invention.

EXAMPLE 1 Butyl-lithium (64 g., 1 mole) in hexane (600 ml.) was added to tetramethyldisilazane (133 g., 1 mole) in pentane (500 m1.). A vigorous reaction occurred and a white solid was precipitated. The solution was stirred for 1 hour and tetrahydrofuran (850 ml.) and chlorotrimethylsilane (108.5 g., 1 mole) was added and the mixture refluxed for hours. The solution was then filtered and distilled to give bis(dimethylsilyl)trimethylsilylamine (139.5 g., 58 percent) b.p. 60 [20 mm. (Found C, 40.6; H, 11.2; N, 6.6; Si, 40.55%; C,H,,Nsi, requires C, 41.0; H, 11.2; N, 6.8; Si, 41.0%).

EXAMPLE 2 EXAMPLE 3 Ammonia was passed into a solution of bis(chlorodimethylsiiyl)trimethylsilylamine (26 g.).in pentane (250 ml.) the reaction being followed by means of vapor phase chromatography. Filtration of the reaction solution, evaporation of solvent and distillation gave 1- trimethylsilyl-Z,2,4,4-tetramethy1cyclodisilazane (l 1.6 g., 56 percent) b.p. 55 mm. (Found: C, 39.3; H, 10.3; N, 12.6; Si, 38.5%; C-,H ,N,Si requires C, 38.55; H, 10.1; N, 12.85; Si, 38.55%). The infra-red and N.M.R. spectra confirmed the cyclic structure.

EXAMPLE 4 Water (1.44 g., 1 molar ratio) was added to 1- trimethylsilyl-2,2,4,4-tetramethylcyclodisilazane 17.2 g., 1 molar ratio) in pentane ml.). After 3 days standing with occasional shaking and stirring, the organic layer was separated, dried over molecular sieve, filtered, evaporated under reduced pressure and distilled to give 1,5-bis(trimethylsilyl)-2,2,4,4,6,6,8,8- octamethyl-l ,5-diaza-3,7-dioxa-2,4,6,3-tetrasilacyclooctane (9.2 g., 54 percent) b.p. 126 /5 mm. (Found: C, 39.0;1-1, 9.83; N, 6.04; Si, 38.0%; C,,,H,, N- ,O Si requires C, 38.4; H, 9.6; N, 6.4; Si, 38.4%).

EXAMPLE 5 Phenol (4.1 g., 2 molar ratio) in benzene (5 ml.) was added to l-trimethylsilyl-2,2,4,4-tetramethylcyclodisilazane (4.8 g., 1 molar ratio) and an exothermic reaction occurred. After 4 hours at room temperature, distillation gave benzene and bis( phenoxydimethylsilyl- )trimethylsilylamine (7.5 g., 88%) b.p. 96 /2 mm., m.p. 37.5". (Found: C, 58.5; H, 8.23; N, 3.66; Si, 21.56; c n no si, requires C, 58.6; H, 7.97; N, 3.6; Si, 21.6%).

That which is claimed is:

1. A novel organosilicon composition of the general formula wherein R" is hydrogen, an alkyl radical containing one to 18 carbon atoms, an alkenyl radical containing two or three carbon atoms or a phenyl radical and each R and R represent an alkyl radical containing less than six carbon atoms, an alkenyl radical selected from the group consisting of vinyl, allyl and cyclohexenyl radicals, a phenyl, p-tolyl or a nitrophenyl radical.

2. A novel organosilicon composition as claimed in claim 1 wherein R" represents a hydrogen atom or a lower alkyl radical.

3. A novel organosilicon composition as claimed in claim 1 wherein the composition is a l-trimethylsilyl- 2,2,4,4-tetrarnethylcyc1odisilazane. i 

2. A novel organosilicon composition as claimed in claim 1 wherein R'''' represents a hydrogen atom or a lower alkyl radical.
 3. A novel organosilicon composition as claimed in claim 1 wherein the composition is a 1-trimethylsilyl-2,2,4,4-tetramethylcyclodisilazane. 